The preparation and administration of medicaments is a complex and frequently error-prone practice. The reason for this is that such preparation and administration requires that various variables relating to the medicament have to be taken into account, which may include, but are not limited to, a required volume of medicament for a given patient's body weight, the volume of required diluent in the case where the medicament requires dilution, or the rate at which a medicament, or medicament and diluent mixture, is required to be administered in the case of an infusion.
Medicament concentrations are commonly indicated in milligram per milliliter (mg/ml), whereas the required dosages of the medicaments are given in milligram per kilogram (mg/kg). Thus, for example, in a case where the medicament to be administered is dependent on the patient's body weight, a series of calculations have to be performed in order to determine the required volume of medicament in milliliters. The calculations in this case would include multiplying the patient's body weight by the required dosage, typically in milligrams per kilogram (mg/kg), which would then provide the total dose of medicament in milligrams (mg). The dose in milligrams (mg) then needs to be divided by the number of milligrams of medicament in each of one or more vials to determine the required volume in milliliters (ml), which can then be drawn into a syringe, and then administered.
The calculation is thus quite complex and may easily result in miscalculations, particularly where the medicament needs to be prepared in a high pressure emergency situation. Nevertheless, miscalculations can evidently also take place in a non-emergency context.
Certain emergency medicaments are administered on occasion for infrequently encountered indications, and even experienced medical providers may be unfamiliar with their use. In addition, certain medicaments may be ordinarily administered by persons who have no special training, such as the parent or caregiver of a patient, who may often not be able to perform the required complex calculations in order to determine the required volume of medicament.
For obvious reasons, the administration of a miscalculated required dosage of medicament can have a variety of detrimental consequences. On the one hand, these detrimental effects can occur as a result of incorrect dosing over a period of time. For example, long term underdosing of anti-infective agents may result in the development of drug resistance. On the other hand, such miscalculations can also have far more immediate effects, particularly when made in the anaesthetic and resuscitation context, where there may be devastating and immediately apparent consequences.
Currently, mass-produced syringes typically have only volume graduations printed on the outside of the syringe barrel. It has been proposed in the prior art to produce syringe labels for application to a syringe, in order to make information available on the outer surface of the syringe barrel, but the information typically includes only the medicament name as well as the medicament concentration.
Although stickers or other markings, which might be applied to some syringes, may be fairly effective in identifying the medicament type and concentration held within a syringe, these markings generally do not assist a user administering the medicament to determine the volume required to be administered, the amount of diluent required, where applicable, or the rate at which such medicament or medicament and diluent mixture should be administered. Furthermore, the markings often found on syringes are informal and non-standardised, having often been made by a practitioner by hand.
The applicant is aware of at least a limited number of syringes, where a pre-printed body weight scale corresponds to certain dosages of a particular medicament. However, the limited application of these pre-printed syringes does not remedy the difficult situation that exists in relation to all other medicaments to be administered in syringes that do not already have the additional information pre-printed thereon.
What is even more crucial, is that solutions to this problem that are to be effective in the developing world as well as the developed world, need to take account of the particular conditions and contexts of hospitals and clinics in poorly resourced environments, in which access to sophisticated equipment, and technology may be limited.
There is thus a pressing need for a solution that alleviates some of the abovementioned problems at least to some extent.
In this specification the term stopper is used to mean the plunger that is movable longitudinally within a barrel of the syringe.